Printer has been widely used in people's life and work. People record data on paper using a printer so as to transfer or save information, for example, printing office documents, supermarket billing details, telephone bill and the like. Generally, to facilitate reading, the data is output onto printing paper in a pre-set format, wherein the pre-set format includes character height, character interval and line spacing; therefore, the more the character is printed, the more the paper is used. With the increased awareness in energy conservation and environment protection, more and more users require the printer to have a paper-saving printing function so as to save printing paper.
At present, in order to achieve the purpose above, a Japanese patent of which the publication number is JP2000289284 provides a printing control system, wherein this printing system further includes a final line verification device that is configured to adjust the character interval of a previous line or the line before the previous line to print the characters of the final line by putting them into the previous line when the original final line to be printed has a few characters; and a final page verification device that is configured to adjust the line spacing in a previous page or the page before the previous page to print the lines of the final page by putting them into the previous page when the original final page to be printed has a few lines.
The inventor finds that the printing system above has defects as follows: it can save one line of printing paper only when the final line to be printed has a few characters, or save one page of printing paper only when the final page to be printed has a few lines; thus, the paper-saving effect is not obvious.